EP4042566A1 - Circuit électrique - Google Patents

Circuit électrique

Info

Publication number
EP4042566A1
EP4042566A1 EP19789889.3A EP19789889A EP4042566A1 EP 4042566 A1 EP4042566 A1 EP 4042566A1 EP 19789889 A EP19789889 A EP 19789889A EP 4042566 A1 EP4042566 A1 EP 4042566A1
Authority
EP
European Patent Office
Prior art keywords
connection
input
switch
output
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19789889.3A
Other languages
German (de)
English (en)
Inventor
Ansgar KIRK
Stefan Zimmermann
Cornelius WENDT
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Leibniz Universitaet Hannover
Original Assignee
Leibniz Universitaet Hannover
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Leibniz Universitaet Hannover filed Critical Leibniz Universitaet Hannover
Publication of EP4042566A1 publication Critical patent/EP4042566A1/fr
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/52—Circuit arrangements for protecting such amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/005—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements using switched capacitors, e.g. dynamic amplifiers; using switched capacitors as resistors in differential amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
    • H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/129—Indexing scheme relating to amplifiers there being a feedback over the complete amplifier
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/156—One or more switches are realised in the feedback circuit of the amplifier stage
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/159—Indexing scheme relating to amplifiers the feedback circuit being closed during a switching time
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/261—Amplifier which being suitable for instrumentation applications
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/372—Noise reduction and elimination in amplifier
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/444—Diode used as protection means in an amplifier, e.g. as a limiter or as a switch
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/462—Indexing scheme relating to amplifiers the current being sensed
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45114—Indexing scheme relating to differential amplifiers the differential amplifier contains another differential amplifier in its feedback circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45116—Feedback coupled to the input of the differential amplifier
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45136—One differential amplifier in IC-block form being shown
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45158—One or more diodes coupled at the inputs of a dif amp as clamping elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45166—Only one input of the dif amp being used for an input signal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45514—Indexing scheme relating to differential amplifiers the FBC comprising one or more switched capacitors, and being coupled between the LC and the IC
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45534—Indexing scheme relating to differential amplifiers the FBC comprising multiple switches and being coupled between the LC and the IC

Definitions

  • the invention relates to an electrical circuit in the form of a transimpedance amplifier stage and a method for operating this circuit.
  • the invention also relates to a circuit with at least one signal amplifier which has at least one output connection, at least one input connection or at least one pair of differential input connections and at least two voltage supply connections, one of which can also be a ground connection, the signal amplifier at least has an additional connection which is internally connected via at least one further component, for example a diode, to at least one of the input connections or the input connection.
  • the invention relates to the field of circuits for signal amplification of electrical signals.
  • Transimpedance amplifiers convert and amplify an input current into a dependent output signal, usually in the form of an output voltage.
  • the essential parameters of a transimpedance amplifier include the possible dynamic range of the input current, the bandwidth and the input current noise. Since the noise generally increases with the bandwidth, the construction of faster, low-noise transimpedance amplifiers requires particularly low noise.
  • transimpedance amplifiers are implemented resistively, logarithmically or, more rarely, capacitively.
  • Resistive transimpedance amplifiers have an ohmic resistance as a feedback element. In order to reduce the input current noise, the resistance must be increased. A low-noise, resistive transimpedance amplifier therefore has a large feedback resistance, which for a large dynamic range means that large output voltage amplitudes of a few hundred volts must be driven. The resulting circuitry effort is therefore impractical.
  • Logarithmic transimpedance amplifiers use a diode or a biopolar transistor as a feedback element and thus compress the output signal. This avoids the need for large output voltage amplitudes. In this case, however, the strong temperature dependence of the feedback properties of the semiconductor components and the relatively large leakage currents which limit the input current range downwards prove to be disadvantageous.
  • Capacitive transimpedance amplifiers have a capacitor as a feedback element.
  • the output voltage corresponds to the integral of the input current over time. Due to the very high insulation resistance of the capacitor, it adds practically no noise in contrast to the ohmic resistance of the resistive transimpedance amplifier.
  • the output voltage amplitude is limited by the integration time, which means that no expensive high-voltage supply is required for a low-noise transimpedance amplifier.
  • the temperature dependence is comparatively low in contrast to the logarithmic transimpedance amplifier. Therefore, the capacitive transimpedance amplifier architecture is ideally suited for a low-noise amplifier with an extremely high dynamic range with currents from a few fA up to a few mA.
  • the reset circuit for discharging the integration capacitor is crucial for a high-performance transimpedance amplifier. Ideally, this should not affect the input path of the transimpedance amplifier.
  • Leakage currents also flow through open switching elements and are often highly temperature-dependent. These cannot be compensated for in a trivial way and thus reduce the input current range significantly. Charge injection is caused by parasitic capacitances in the switching element, which shift charge to the input path when the switching element is opened or closed, thus causing parasitic input currents and possibly even saturating the integration capacitor. In addition, closed switching elements have a resistance greater than zero and thereby impede the flow of current and thus rapid discharge.
  • the invention is based on the object of specifying an electrical circuit in the form of a transimpendance amplifier stage with improved operating data and a method for operating such a circuit. Furthermore, an improved circuit with at least one signal amplifier of the type mentioned above is to be indicated.
  • an electrical circuit in the form of a transimpedance amplifier stage having an input node, an output node and a feedback node, with the following features: a) at least one signal amplifier, the at least one output connection and at least one input connection or at least one pair differential input connections, wherein an input signal applied to at least one input connection is converted into a multiply amplified output signal emitted at the output connection, the output connection directly or via at least one further component to the output node and at least one of the input connections directly or is connected or connectable to the input node via at least one further component, the reference potential of the signal amplifier in the case of a single input connection or the reference potential of the signal amplifier in the case of a pair of differential input connection e the potential of the other input terminal that is not or cannot be connected to the input node is referred to as the first reference potential, b) at least one feedback element which is connected to a first terminal directly or via at least one further component to the input node and to a second Connection is connected or connectable
  • the circuit according to the invention has the advantage that a capacitive or at least partially capacitive transimpedance amplifier architecture can be provided in which a very efficient resetting of the feedback element, for example a discharge of the feedback capacitor, is possible via the existing switches.
  • the circuit has practically no interference from leakage currents from the existing switches.
  • the existing switches can be switched at high speed with low charge injection. This is made possible by the fact that the feedback element is not short-circuited via the non-ideal switching element as in previous circuits, but rather the voltage across the feedback element is actively regulated to a certain value, for example zero.
  • the circuit allows a feedback capacitor to be discharged actively and extremely quickly without significantly affecting the input path.
  • the electrical circuit is suitable, for example, as a signal amplifier for highly sensitive measuring devices, for example for gas chromatographs, ion mobility spectrometers, mass spectrometers, other types of spectrometers or analyzers for electrical material parameters.
  • the signal amplifier usually has a high gain factor, for example at least 1000 or at least 10000 Example, be designed as an operational amplifier, advantageously as an electrometer amplifier with low leakage currents.
  • the first reference potential can be a fixed (unchangeable) voltage potential, in particular also the ground potential of the circuit.
  • a variable potential could also be used to change the properties of the circuit during operation.
  • an electrical circuit in the form of a transimpedance amplifier stage the circuit having an input node and an output node, with the following features: a) at least one signal amplifier, which has at least one output connection and at least one input connection or at least one pair of differential Ler input connections, wherein an input signal applied to at least one input connection is converted into a multiply amplified output signal emitted at the output connection, the output connection directly or via at least one further component to the output node and at least one of the input connections directly or via at least Another component is connected or connectable to the input node, the reference potential of the signal amplifier in the case of a single input connection or the potential in the case of a pair of differential input connections tial of the other input connection, which is not or cannot be connected to the input node, is referred to as the first reference potential, b) at least one feedback element which is connected to a first connection directly or via at least one further component to the input node and to a second connection directly or is connected or connectable to the output
  • the further output terminal being connected directly or via at least one further component to a second switch and at least one further input terminal is connected to the output node directly or via at least one further component, with the Reference potential of the further signal amplifier or, in the case of a further pair of differential input connections, the potential of the other further input connection, which is not connected to the output node or which can be closed, is referred to as the second reference potential, d) at least the second switch through which the further output connection un indirectly or can be connected to the input node via at least one further component.
  • the second signal amplifier can take over the control according to the invention, by means of which the feedback element is reset to the neutral state, without the first or second connection of the feedback element having to be directly connected to one another (short-circuited). Instead, the further signal amplifier is switched between the output node and the second switch.
  • the second reference potential can be a potential that is separate from the first reference potential or a potential that is connected (short-circuited) to the first reference potential.
  • These elements only represent the basic structure of the circuit. For example, additional signal amplifiers or multiple inverters of the signal can be inserted between these elements without changing the way the circuit works.
  • the feedback element can, for example, have a third connection which is at any reference potential.
  • the feedback element is formed by a resistor, a capacitor or a circuit composed of one or more resistors and / or one or more condensers. This allows a simple implementation of the feedback element as well as a particularly effectively working transimpedance amplifier high sensitivity. It is advantageous if the feedback element has at least one capacitive component.
  • the feedback control element is formed by a resistor, a capacitor or a circuit composed of one or more resistors and / or one or more capacitors.
  • This allows a simple implementation of the feedback control element and a particularly effective transimpedance amplifier with high sensitivity.
  • the feedback node can thus optionally, that is, when the first switch is brought into a certain switch position, be connected to the second reference potential and be separated from the second reference potential in another switch position.
  • the first switch can, for example, be designed as a simple on / off switch. The fact that the feedback node can in this case be connected to the output connection of the signal amplifier via the feedback control element does not affect the circuit as long as the impedance of the feedback control element is high compared to the impedance of the closed first switch, for example at least ten times as high.
  • the output connection of the signal amplifier can be connected to the input node when the switch is in a corresponding switch position or, when the switch is in a different switch position, separated therefrom.
  • the second switch can be designed, for example, as an on / off switch.
  • the circuit according to the invention makes it possible, through the arrangement of the first and the second switch, in particular that the feedback element is reset to a neutral state, for example by its first and second connection can be set to practically the same voltage potential without the first or second connection having to be directly connected to one another (short-circuited).
  • the first and the second switch can in particular be switches that can be controlled by electrical control signals.
  • the switches can have galvanic switching contacts, semiconductor switches, signal amplifiers with an output that can be switched off and / or signal amplifiers with an input hysteresis.
  • the first and / or second switch can be designed as an analog switch. Such analog switches allow reliable and fast switching. However, depending on the embodiment, this can generate additional interference effects, for example through leakage current and / or charge injection from the analog switch.
  • the second reference potential corresponds to the first reference potential.
  • the feedback element can be reset, for example discharging the capacitor, quickly and at the same time without impairing the input path.
  • the functionality of the signal amplifier can be used, which, due to its high gain factor, strives to keep the potential difference between its input terminal and the first reference potential low and accordingly to keep it practically at the same potential. This also compensates for voltage drops at the switches and other components in the discharge path that would otherwise impair discharge.
  • the first and the second connection of the feedback element are virtually short-circuited, so to speak, since the first and the second connection can be brought to the same voltage potential as a result by the first and the second switch.
  • the feedback element for example a capacitor
  • the feedback element can then be precharged to a predefined voltage which corresponds to the difference between these voltage potentials.
  • at least one current limiting element is connected in series to the second switch, which has a current transfer characteristic through which small currents, in particular leakage currents of the second switch, are prevented and larger currents are allowed to pass. In other words, when the voltage is low, practically no current flows, but when the voltage is higher, a current that is much greater than the ratio of these voltages is greater.
  • the current limiting element can, for example, be a diode or a circuit made up of diodes, for example two diodes connected in anti-parallel, or a corresponding circuit made up of JFETs (JFET - Junction Field Effect Transistor). Any interference effects of the first and / or second switch, for example leakage current and / or charge injection, can be further minimized here.
  • the cited parts of the circuit can each be designed as separate components, that is to say as discrete components.
  • the feedback element, the feedback control element, the current limiting element, the first switch and the second switch can be designed as separate components from the signal amplifier.
  • the current limiting element is formed by protective diodes integrated in the signal amplifier. This has the advantage that no additional components are required for the formation of the current limiting element. Another, particularly important advantage for a transimpedance amplifier stage with high sensitivity is that by using integrated protective diodes already present in the signal amplifier, the input path of the circuit is in no way affected by the current limiting element or the other parts connected to the first switch and / o connected to the second switch is affected. Only the input of the signal amplifier and the first connection of the feedback element then need to be connected to the input node.
  • the first and the second switch can be controlled by electrical control signals
  • the circuit has a control device for controlling the switching of the first and the second switch, wherein the control device is configured to switch the first and the second switch to switch positions in a first operating mode, through which a current flowing into the input node is converted into a ver stronger, integrated or otherwise dependent output signal is converted at the output node of the circuit, and in a second operating mode to switch the first and second switches to switch positions through which the circuit, in particular the feedback element, is actively regulated into a neutral state.
  • the control device thus emits the electrical control signals to the first and second switches in order to selectively activate the first operating mode or the second operating mode.
  • the control device can accordingly at regular or irregular time intervals, for example in a fixed cycle in the millisecond range, if this is specified from outside, if the last change of the operating mode was a certain time ago or if the output voltage of the signal amplifier exceeds a certain threshold value first and second switch switch from the first operating mode to the second operating mode, etc.
  • the circuit in particular the feedback element, is reset to the neutral state at certain times. Capacitive components of the feedback element can be discharged quickly in this way.
  • the second operating mode is only activated for a relatively short time, so that the circuit is operated in the first operating mode for most of the time, in which the input signals can be detected by means of the transimpedance amplifier stage and output as amplified output signals and measurements can be carried out accordingly.
  • the pulse duty factor with which the second operating mode is activated can be 10% or less.
  • the control device can, for example, be designed in terms of hardware as a clock generator, as configurable hardware such as FPGA or CPLD, or it can be a microprocessor-controlled device that executes a computer program by which the electrical control signals for controlling the first and second switches are generated and output .
  • an external control signal can be used to reset the transimpedance amplifier in a targeted manner, for example during a period in which disturbances are expected due to switching processes.
  • the control device is set up to switch the first and the second switch in the same way. If the first and the second switch are each designed as an on / off switch, the second switch is always in the “On” state when the first switch is in the “On” state, and the second switch is in the " Off "when the first switch is in the” Off “state.
  • the feedback control element is designed as a third switch which is switched by the control device opposite to the first switch.
  • the first and third switches can advantageously be implemented by a single changeover switch instead of two on / off switches, which takes over their switching function.
  • the aforementioned object is also achieved by a method for operating a circuit of the type explained above, in which the feedback element is reset by actively regulating the voltage across the feedback element to a certain value, for example zero.
  • the feedback element is not short-circuited via a non-ideal switching element as in previous circuits, but actively controlled, e.g. by means of the signal amplifier.
  • a current flowing in the input node is converted into an amplified, integrated or otherwise dependent output signal at the output node of the circuit and a second operating mode of the circuit, the circuit, in particular the Feedback element, is actively regulated into a neutral state, switching between the first and the second operating mode.
  • the first operating mode is thus a Häbe operating mode of the circuit
  • the second operating mode is a reset operating mode of the circuit.
  • the first signal amplifier is not unity gain stable, to insert an additional compensation network in the circuit path with the second switch or to give the second signal amplifier a special frequency response so that it is ensured that the noise gain of the circuit is sufficiently high for stable operation of the first signal amplifier in both cases.
  • the output node is coupled to a differentiator.
  • a final output signal can be provided that is adjusted for any integrating influence of the feedback element that may be present, for example if it has a capacitance.
  • the differentiator can, for example, be designed using analog technology, that is to say as an analog differentiator.
  • the differentiator can also be implemented digitally, for example with an analog-digital converter and a computer, microcontroller or FPGA connected to the analog-digital converter, on which the differentiation is carried out using digital computing steps.
  • conventional filter circuits are advantageously connected to limit the signal bandwidth between the transimpedance amplifier stage and the analog-digital converter.
  • the signal received from the output terminal of the signal amplifier is differentiated according to time.
  • the digitized signal can advantageously also be evaluated to trigger the control device.
  • the frequency of the reset signal generated when a certain output voltage is exceeded can also be evaluated in order to determine the average current that has flowed during this period.
  • a circuit with at least one signal amplifier which has at least one output connection, at least one input connection or at least one pair of differential input connections and at least two voltage supply connections, one of which ner can also be a ground or ground connection
  • the signal amplifier has at least one additional connection which is internally connected via at least one further component, for example a diode, to at least one of the input connections or the input connection
  • the Circuit we have at least one component connected to this connection, through which an electrical current is fed into this connection or an electrical voltage is applied to this connection.
  • connections can also be used here that are actually configured as an output for a signal, as is apparent to the person skilled in the art.
  • the component mentioned above can be, for example, a further signal amplifier or a line connected to a specific potential.
  • this additional connection can be a so-called guard connection, which normally serves to isolate input connections from leakage currents on or through a printed circuit board or die on which the signal amplifier is arranged.
  • the signal amplifier can, for example, have a guard circuit in which a pair of antiparallel-connected diodes are connected between the guard connection and the positive input connection and / or a pair of antiparallel-connected diodes are connected between the guard connection and the negative input connection .
  • the guard connection can also be connected to further components, for example to a guard buffer. According to the invention it has now been found that a signal amplifier with such a guard connection can also be applied in other ways, for example to eliminate components that would otherwise be necessary for external wiring of the signal amplifier and to replace them with parts of the guard circuit of the Signalver amplifier.
  • two diodes connected in anti-parallel can be used to reduce leakage current interference from the analog switches.
  • these externally connected diodes can be omitted, as will be explained in more detail below with reference to an exemplary embodiment.
  • the invention is explained in more detail below with reference to exemplary embodiments using drawings. Show it
  • Fig. 1 - a first embodiment of an electrical circuit
  • FIG. 4 - a third embodiment of an electrical circuit in a first and a second operating mode and FIG. 6 - a fourth embodiment of an electrical circuit and
  • Fig. 7 - a fifth embodiment of an electrical circuit
  • Fig. 8 - a sixth embodiment of an electrical circuit.
  • circuits shown in FIGS. 1 to 8 are each shown by way of example as a transimpedance amplifier stage. Other embodiments are also possible.
  • FIG. 1 shows the circuit with a signal amplifier V1, a feedback element RE, a first switch S1 and a second switch S2.
  • the signal amplifier V1 has a negative input connection 1, a positive input connection 2 and an output connection 3.
  • the first switch S1 and the second switch S2 are shown by way of example as on / off switches. They each have two switch positions. In one switch position a contact C is connected to a contact A of the respective switch S1, S2, in another switch position the switches are open.
  • An input signal to be measured is fed in at the input node IN, in this case an input current IIN.
  • the input node IN is connected to the negative input connection 1, a first connection of the feedback element RE and the contact C of the second switch S2.
  • the positive input connection 2 is connected to a fixed voltage potential, the first reference potential REF1, for example ground potential.
  • the output connection 3 is connected to the output node at which the output signal UOUT is provided. This is also connected to the contact A of the second switch S2 and the first connection of the feedback control element RSE.
  • the second connection of the feedback element RE, the second connection of the feedback control element RSE and the contact A of the first switch S1 are connected to the feedback node FB.
  • the contact C of the first switch S1 is connected to a second reference potential REF2, for example to the ground potential.
  • various exemplary embodiments of the feedback control element are shown, for example a resistor R1, a network N1 and an on / off switch S3.
  • the circuit is in a first operating mode in which the normal measurement and amplification function of the transimpedance amplifier stage can be carried out.
  • FIG. 2 shows an exemplary embodiment in which a capacitor CF is used as the feedback element RE and a switch S3, which switches in the opposite direction to S1 and connects the contacts A and B, as the feedback control element.
  • the on / off switches S1 and S3 have advantageously been combined to form a changeover switch S1.
  • FIG. 2 shows the circuit in a first operating mode in which the normal measurement and amplification function of the transimpedance amplifier stage can be carried out.
  • a connection is established between the output connection 3 and the second connection of the feedback element CF via the first switch S1.
  • the output connection 3 is separated from the negative input connection 1 by the second switch S2.
  • the circuit can be operated, for example, as a conventional capacitive transimpedance amplifier stage.
  • the current / / w supplied on the input side is converted into a multiply amplified or integrated output signal UOUT via the transimpedance amplifier stage.
  • the feedback element CF may be discharged in order to avoid disruptive effects, if due to the integrating function, the maximum permissible voltage is reached at the feedback element CF.
  • the circuit is brought into a second operating mode, which is shown in FIG.
  • the first and the second switch S1, S2 are switched over in comparison to FIG.
  • the second connection of the feedback element CF is now connected via the first switch S1 to the contact C and thus to the second reference potential which is connected there.
  • a connection between the output connection 3 and the negative input connection 1 and thus also with the first connection of the feedback element CF is established via the second switch S2.
  • the feedback element CF is quickly discharged or charged by the signal amplifier V1 to a voltage which corresponds to the potential difference between the second reference potential at the contact C of the first switch S1 and the first reference potential at the positive input terminal 2. If the voltage difference between these voltage potentials is equal to zero, the feedback element CF is thus completely discharged.
  • FIGS. 4 and 5 show an embodiment of the circuit which differs from FIGS. 2 and 3 in that a current limiting element D1, D2 is connected in series in the connection from the output connection 3 via the second switch S2 to the negative input connection 1 .
  • the current limiting element D1, D2 can be designed as two anti-parallel connected diodes. In this way, interference effects from leakage currents and / or charge injections due to the first and second switches S1, S2 can be further minimized.
  • FIG. 4 shows the circuit in the first operating mode
  • FIG. 5 shows the circuit in the second operating mode. The mode of operation otherwise corresponds to the mode of operation of the circuit in FIGS. 2 and 3.
  • FIG. 6 shows a further variant of the circuit in which the feedback control element RSE has been replaced by a short circuit and which thereby removes over liquid switch S1.
  • the second connection of the feedback element RE in this case the capacitor C F , is thus connected directly to the output node OUT. Since the output of the signal amplifier V1 is now permanently connected to the second Connection of the feedback element is connected, it can no longer fulfill the control function according to the invention.
  • a second signal amplifier V2 is connected with its positive input to the output node, with its negative input to the second reference potential and with its output to contact A of switch S2. This also endeavors to minimize the potential difference between its inputs and now drives a current into the input node until the potential at the second connection of the feedback element corresponds to the second reference potential.
  • FIG. 7 shows an embodiment of the circuit which, like the embodiment of FIGS. 4 and 5, has a current limiting element D1, D2 in series with the second switch S2.
  • the current limiting element D1, D2 is in this case not implemented by an external diode circuit, but rather by protective diodes integrated into the Signalver stronger V1.
  • a guard connection 4 of the signal amplifier V1 can be used.
  • the second switch S2 is then simply connected to the guard connection 4. Due to the internal wiring of the signal amplifier V1, the connection via the current limiting element D1, D2 to the negative input terminal 1 is already established.
  • FIG. 8 shows the circuit known from FIG. 6, likewise using a current limiting element implemented via protective diodes D1, D2 integrated in the signal amplifier V1.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)

Abstract

La présente invention concerne un circuit électrique sous la forme d'un étage d'amplificateur à transimpédance et un procédé d'actionnement de ce circuit. L'invention concerne en outre un circuit contenant au moins un amplificateur de signal qui présente au moins une connexion de sortie, au moins une connexion d'entrée ou au moins une paire de connexions d'entrée différentielles et au moins deux connexions d'alimentation en tension, dont l'une peut également être une connexion à la terre ou à la masse, l'amplificateur de signal présentant au moins une connexion supplémentaire qui est connectée en interne à au moins l'une des connexions d'entrée ou à la connexion d'entrée par l'intermédiaire d'au moins un autre composant, par exemple une diode.
EP19789889.3A 2019-10-09 2019-10-09 Circuit électrique Pending EP4042566A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2019/077364 WO2021069071A1 (fr) 2019-10-09 2019-10-09 Circuit électrique

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EP4042566A1 true EP4042566A1 (fr) 2022-08-17

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EP19789889.3A Pending EP4042566A1 (fr) 2019-10-09 2019-10-09 Circuit électrique

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US (1) US20220376660A1 (fr)
EP (1) EP4042566A1 (fr)
WO (1) WO2021069071A1 (fr)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4068278A (en) * 1976-05-27 1978-01-10 Williams Bruce T Overload protection circuit for amplifiers
US4044313A (en) * 1976-12-01 1977-08-23 Rca Corporation Protective network for an insulated-gate field-effect (IGFET) differential amplifier
JP3337241B2 (ja) * 1991-07-26 2002-10-21 テキサス インスツルメンツ インコーポレイテツド 改良型多重チャンネル・センサーインターフェース回路とその製造方法
WO2001075455A2 (fr) * 2000-04-04 2001-10-11 Rosemount Aerospace Inc. Accelerometre trois axes
US8552355B2 (en) * 2008-04-24 2013-10-08 Panasonic Corporation Smoke sensor including a current to voltage circuit having a low frequency correction means to produce a correction current
MX338219B (es) 2012-06-01 2016-04-06 Smiths Detection Watford Ltd Amplificador de transimpedancia con condensador integrado.

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US20220376660A1 (en) 2022-11-24

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